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NASA's Next Leap in Mars Exploration Nears Arrival

02.24.06

As it nears Mars on March 10, a NASA spacecraft designed to examine
the red planet in unprecedented detail from low orbit will point its
main thrusters forward, then fire them to slow itself enough for Mars'
gravity to grab it into orbit.

Ground controllers for Mars Reconnaissance Orbiter expect a signal shortly
after 1:24 p.m. Pacific time (4:24 p.m. Eastern time) that this mission-critical
engine burn has begun. However, the burn will end during a suspenseful half hour
with the spacecraft behind Mars and out of radio contact.

"This mission will greatly expand our scientific understanding of Mars, pave
the way for our next robotic missions later in this decade, and help us prepare
for sending humans to Mars," said Doug McCuistion, Director of NASA's Mars
Exploration Program. "Not only will Mars Science Laboratory's landing and
research areas be determined by the Mars Reconnaissance Orbiter, but the
first boots on Mars will probably get dusty at one of the many potential
landing sites this orbiter will inspect all over the planet."

The orbiter carries six instruments for studying every level of Mars from
underground layers to the top of the atmosphere. Among them, the most powerful
telescopic camera ever sent to a foreign planet will reveal rocks the size of
a small desk. An advanced mineral-mapper will be able to identify water-related
deposits in areas as small as a baseball infield. Radar will probe for buried
ice and water. A weather camera will monitor the entire planet daily. An infrared
sounder will monitor atmospheric temperatures and the movement of water vapor.

The instruments will produce torrents of data. The orbiter can pour data to Earth
at about 10 times the rate of any previous Mars mission, using a dish antenna 3
meters (10 feet) in diameter and a transmitter powered by 9.5 square meters
(102 square feet) of solar cells. "This spacecraft will return more data than all
previous Mars missions combined," said Jim Graf, project manager for Mars
Reconnaissance Orbiter at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Scientists will analyze the information to gain a better understanding of changes
in Mars' atmosphere and the processes that have formed and modified the planet's
surface. "We're especially interested in water, whether it's ice, liquid or vapor,"
said JPL's Dr. Richard Zurek, project scientist for the orbiter. "Learning
more about where the water is today and where it was in the past will also
guide future studies about whether Mars has ever supported life."

A second major job for Mars Reconnaissance Orbiter, in addition to its own
investigation of Mars, is to relay information from missions working on the
surface of the planet. During its planned five-year prime mission, it will
support the Phoenix Mars Scout, which is being built to land on icy soils
near the northern polar ice cap in 2008, and the Mars Science Laboratory,
an advanced rover under development for launch in 2009.

However, before Mars Reconnaissance Orbiter can begin its main assignments,
it will spend half a year adjusting its orbit with an adventurous process
called aerobraking. The initial capture by Mars' gravity on March 10 will
put the spacecraft into a very elongated, 35-hour orbit. The planned orbit
for science observations is a low-altitude, nearly circular, two-hour loop.
To go directly into an orbit like that when arriving at Mars would have required
carrying much more fuel for the main thrusters, requiring a larger and more
expensive launch vehicle and leaving less payload weight for science instruments.
Aerobraking will use hundreds of carefully calculated dips into the upper
atmosphere -- deep enough to slow the spacecraft by atmospheric drag,
but not deep enough to overheat the orbiter.

"Aerobraking is like a high-wire act in open air," Graf said. "Mars' atmosphere
can swell rapidly, so we need to monitor it closely to keep the orbiter at an
altitude that is effective but safe." Current orbiters at Mars will provide
a daily watch of the lower atmosphere, an important example of the cooperative
activities between missions at Mars.

Additional information about Mars Reconnaissance Orbiter is available online at:

The mission is managed by JPL, a division of the California Institute of
Technology, Pasadena, for the NASA Science Mission Directorate, Washington.
Lockheed Martin Space Systems, Denver, is the prime contractor for the
project and built the spacecraft.